Discussion :

[Sahengette]

Bonjour, j'essaye en ce moment d'apprendre à utiliser boost::spirit et je me suis imposé en lisant la doc un petit exercice, récuperer l'extension d'un nom de fichier.
Par exemple "toto.jpg" son extension est jpg .
Voici le code complet de ma grammaire spirit :

Code :

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#include <boost/config/warning_disable.hpp>
#include <iostream>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix_operator.hpp>
namespace qi = boost::spirit::qi;
namespace ascii = boost::spirit::ascii;
 
struct extension : qi::grammar<std::string::const_iterator, std::string(), ascii::space_type>
{
	extension() : extension::base_type(start)
	{
		using ascii::char_;
		start = *(char_ - '.') >> '.' >> *(char_[qi::_val += qi::_1]);
	}
	qi::rule<std::string::const_iterator, std::string(), ascii::space_type> start;
};
 
int main()
{
	std::string test("test.ext");
	extension grammaire;
	std::string resultat;
 
	qi::phrase_parse(test.begin(), test.end(), grammaire, ascii::space, resultat);
        std::cout << resultat << std::endl;
        return 0;
}

Voila l'erreur de compilation (je dois avouer que je la trouve ... imbitable ) :

Code :

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In file included from /usr/include/boost/spirit/home/qi/nonterminal/rule.hpp:35:0,
                 from /usr/include/boost/spirit/home/qi/nonterminal.hpp:14,
                 from /usr/include/boost/spirit/home/qi.hpp:20,
                 from /usr/include/boost/spirit/include/qi.hpp:16,
                 from /home/theodor/Programme/BBEngine/src/BBEngine/MeshParser.cpp:3:
/usr/include/boost/spirit/home/qi/reference.hpp: In instantiation of ‘bool boost::spirit::qi::reference<Subject>::parse(Iterator&, const Iterator&, Context&, const Skipper&, Attribute&) const [with Iterator = __gnu_cxx::__normal_iterator<char*, std::basic_string<char> >; Context = boost::spirit::context<boost::fusion::cons<std::basic_string<char>&, boost::fusion::nil>, boost::spirit::locals<> >; Skipper = boost::spirit::qi::char_class<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >; Attribute = std::basic_string<char>; Subject = const boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, std::basic_string<char>(), boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type>]’:
/usr/include/boost/spirit/home/qi/parse.hpp:164:9:   required from ‘bool boost::spirit::qi::phrase_parse(Iterator&, Iterator, const Expr&, const Skipper&, boost::spirit::qi::skip_flag::enum_type, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<char*, std::basic_string<char> >; Expr = extension; Skipper = boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>; Attr = std::basic_string<char>]’
/usr/include/boost/spirit/home/qi/parse.hpp:210:86:   required from ‘bool boost::spirit::qi::phrase_parse(const Iterator&, Iterator, const Expr&, const Skipper&, Attr&) [with Iterator = __gnu_cxx::__normal_iterator<char*, std::basic_string<char> >; Expr = extension; Skipper = boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>; Attr = std::basic_string<char>]’
/home/theodor/Programme/BBEngine/src/BBEngine/MeshParser.cpp:24:78:   required from here
/usr/include/boost/spirit/home/qi/reference.hpp:43:71: erreur: no matching function for call to ‘boost::spirit::qi::rule<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, std::basic_string<char>(), boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type>::parse(__gnu_cxx::__normal_iterator<char*, std::basic_string<char> >&, const __gnu_cxx::__normal_iterator<char*, std::basic_string<char> >&, boost::spirit::context<boost::fusion::cons<std::basic_string<char>&, boost::fusion::nil>, boost::spirit::locals<> >&, const boost::spirit::qi::char_class<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >&, std::basic_string<char>&) const’
/usr/include/boost/spirit/home/qi/reference.hpp:43:71: note: candidates are:
In file included from /usr/include/boost/spirit/home/qi/nonterminal.hpp:14:0,
                 from /usr/include/boost/spirit/home/qi.hpp:20,
                 from /usr/include/boost/spirit/include/qi.hpp:16,
                 from /home/theodor/Programme/BBEngine/src/BBEngine/MeshParser.cpp:3:
/usr/include/boost/spirit/home/qi/nonterminal/rule.hpp:273:14: note: template<class Context, class Skipper, class Attribute> bool boost::spirit::qi::rule::parse(Iterator&, const Iterator&, Context&, const Skipper&, Attribute&) const [with Context = Context; Skipper = Skipper; Attribute = Attribute; Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >; T1 = std::basic_string<char>(); T2 = boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>; T3 = boost::spirit::unused_type; T4 = boost::spirit::unused_type]
/usr/include/boost/spirit/home/qi/nonterminal/rule.hpp:273:14: note:   template argument deduction/substitution failed:
In file included from /usr/include/boost/spirit/home/qi/nonterminal/rule.hpp:35:0,
                 from /usr/include/boost/spirit/home/qi/nonterminal.hpp:14,
                 from /usr/include/boost/spirit/home/qi.hpp:20,
                 from /usr/include/boost/spirit/include/qi.hpp:16,
                 from /home/theodor/Programme/BBEngine/src/BBEngine/MeshParser.cpp:3:
/usr/include/boost/spirit/home/qi/reference.hpp:43:71: note:   cannot convert ‘first’ (type ‘__gnu_cxx::__normal_iterator<char*, std::basic_string<char> >’) to type ‘__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >&’
In file included from /usr/include/boost/spirit/home/qi/nonterminal.hpp:14:0,
                 from /usr/include/boost/spirit/home/qi.hpp:20,
                 from /usr/include/boost/spirit/include/qi.hpp:16,
                 from /home/theodor/Programme/BBEngine/src/BBEngine/MeshParser.cpp:3:
/usr/include/boost/spirit/home/qi/nonterminal/rule.hpp:319:14: note: template<class Context, class Skipper, class Attribute, class Params> bool boost::spirit::qi::rule::parse(Iterator&, const Iterator&, Context&, const Skipper&, Attribute&, const Params&) const [with Context = Context; Skipper = Skipper; Attribute = Attribute; Params = Params; Iterator = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >; T1 = std::basic_string<char>(); T2 = boost::proto::exprns_::expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::spirit::tag::char_code<boost::spirit::tag::space, boost::spirit::char_encoding::ascii> >, 0l>; T3 = boost::spirit::unused_type; T4 = boost::spirit::unused_type]
/usr/include/boost/spirit/home/qi/nonterminal/rule.hpp:319:14: note:   template argument deduction/substitution failed:
In file included from /usr/include/boost/spirit/home/qi/nonterminal/rule.hpp:35:0,
                 from /usr/include/boost/spirit/home/qi/nonterminal.hpp:14,
                 from /usr/include/boost/spirit/home/qi.hpp:20,
                 from /usr/include/boost/spirit/include/qi.hpp:16,
                 from /home/theodor/Programme/BBEngine/src/BBEngine/MeshParser.cpp:3:
/usr/include/boost/spirit/home/qi/reference.hpp:43:71: note:   cannot convert ‘first’ (type ‘__gnu_cxx::__normal_iterator<char*, std::basic_string<char> >’) to type ‘__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >&’
make[2]: *** [CMakeFiles/bin/bin.dir/src/BBEngine/MeshParser.cpp.o] Erreur 1
make[1]: *** [CMakeFiles/bin/bin.dir/all] Erreur 2
make: *** [all] Erreur 2
 
le shell a retourné 2

Malheureusement je ne sais pas quoi faire maintenant, je ne crois pas m'être trompé dans la grammaire ou dans les espaces de noms, et je crois que le problème se situe sur la ligne ou j'appelle phrase_parse.

J'espere que vous pourrez m'aider, merci de m'avoir lu !

[Arzar]

Bonjour,

cannot convert ‘first’ (type ‘__gnu_cxx::__normal_iterator<char*, std::basic_string<char> >’) to type ‘__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >&’

Ça ressemble beaucoup à un problème de constness, non ? Cannot convert normal_iterator<char*,...> to normal_iterator<const char*,...>

Essaye de remplacer tous les std::string::const_iterator par des std::string::iterator

Ça me semble d'autant plus probable que spirit dans la fonction phrase_parse incrémente l'itérateur passé en premier paramètre pour le faire pointer à l'endroit où le parsing s'est arrêté (en cas d’échec, quelque part au milieu de la string, en cas de réussite à la fin de la string).

C'est à dire que si tu fais :

Code :

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std::string::iterator it = test.begin();
std::string::iterator end = test.end();
qi::phrase_parse(it, end, grammaire, ascii::space, resultat);
        std::cout << resultat << std::endl;

Alors si le parsing a réussi tu as (it == end) en sorti de phrase_parse(). "it" doit donc être modifiable et ne peut pas être un const_iterator.

[Sahengette]

Merci beaucoup, j'ai bêtement copié des bouts de codes sans réfléchir, je n'ai que ce que je mérite.
Maintenant ca marche à merveille, merci !